A network-on-chip (NoC) is a packet based interconnection for transporting read and write transactions between socket interfaces. A NoC comprises at least one initiator network interface unit (NIU) and at least one target NIU. Initiator NIUs convert transaction requests at the initiator socket interface to request packets and converts response packets to transaction responses at the initiator socket interface. Target NIUs convert request packets to transaction requests at the target socket interface and converts transaction responses at the target socket interface to response packets. Initiator NIUs and target NIUs are connected through a topology of switches. The packets may contain a field known as a sequence ID, which encodes some or all of: the initiator ID, target ID, transaction sequence ID, and transaction tag.
Conventional target NIUs, upon receiving transaction responses, perform a context array look up that requires a search of all context array entries and logic to deduce the oldest entry in the chain matching the response packet sequence ID. This requires a lot more logic silicon area than a simple index. More importantly, the logic for the chained list look-up is deeper in logic levels and therefore has longer, slower, timing paths. Therefore what is needed is a system and method for connecting two NoCs that has faster timing and less logic.